CVE-2021-42112Public exploitNetwork attack vector

Stored script execution via unsafe JSON eval

Published Oct 8, 2021 · Updated Aug 4, 2024

Stored cross-site scripting in LimeSurvey 3.x-LTS through 3.27.18 allows remote attackers to run script in a victim's browser. The file-upload question scripts pass stored, attacker-controlled JSON text to JavaScript eval(), interpreting embedded code instead of parsing data. Exploitation requires a survey with a File Upload question and a victim to open a crafted link; the script executes in the LimeSurvey origin and can access session data or act as the victim.

CVSS severity6.1
Medium
EPSS probability1.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in LimeSurvey 3.x-LTS through 3.27.18 allows remote attackers to run script in a victim's browser. The file-upload question scripts pass stored, attacker-controlled JSON text to JavaScript eval(), interpreting embedded code instead of parsing data. Exploitation requires a survey with a File Upload question and a victim to open a crafted link; the script executes in the LimeSurvey origin and can access session data or act as the victim.

The record

CVE
CVE-2021-42112
Published
Oct 8, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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